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Method for continuously preparing 2-(2-nitrophenyl) ethanol

A nitrophenyl, continuous method technology, applied in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc., can solve problems such as high energy consumption of rectification, reduced heat exchange efficiency, loss of catalytic effect, etc.

Pending Publication Date: 2022-04-29
CHANGZHOU FEIYU CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The method adopts a large excess of 2-nitrotoluene to suppress the generation of by-product double substitutions. Although a higher yield can be obtained, it also causes the conversion rate of 2-nitrotoluene to be less than 50% each time. The rectification recovery is put into the next reaction. The equipment efficiency of the whole process is low, and the energy consumption of multiple rectifications is high, which does not meet the theme of energy conservation and environmental protection in today's society.
This reaction is an exothermic reaction. When the scale becomes larger, the heat transfer efficiency will decrease, which will easily lead to excessive local temperature and generate more by-products. In addition, because NaOH catalyzes the Cannizzaro reaction of formaldehyde itself, formic acid and methanol are generated. Formic acid Consumption of NaOH will cause the pH value of the system to decrease, and then gradually lose the catalytic effect. If NaOH is added, the generation of by-products will be significantly increased, which is another reason for the low efficiency of the system

Method used

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  • Method for continuously preparing 2-(2-nitrophenyl) ethanol
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  • Method for continuously preparing 2-(2-nitrophenyl) ethanol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] 2-nitrotoluene was dissolved in DMSO to prepare a solution with a mass concentration of 40%, and tetra-n-butylammonium hydroxide equivalent to 1% of the molar weight of 2-nitrotoluene was added, and the solution was defined as solution A;

[0038] Mix 80% formaldehyde aqueous solution with DMSO to prepare a formaldehyde solution with a mass concentration of 20%, which is defined as B;

[0039] Use a metering pump to pump the two streams of materials A and B into a tubular reactor made of stainless steel for continuous reaction. The tubular reactor is soaked in a constant temperature water bath at 45°C in advance, and the flow rate is controlled by two metering pumps to achieve material The molar ratio is 2-nitrotoluene: formaldehyde = 1:0.8, residence time = 45min. The reaction solution flowing out from the reactor directly flows into the excess NaHSO 4 Quench the powder in a large beaker. Collect the effluent for a period of time (such as 20 minutes), obtain the weig...

Embodiment 2

[0041] Adopt the method of embodiment 1, change the concentration of A, B two stock materials, other parameters are constant, investigate the impact of different concentrations on reaction result, specifically see table 1:

[0042] Table 1, the impact of different concentrations on the reaction results

[0043]

[0044] The result of table 1 shows: concentration too low or too high all have unfavorable influence to reaction, when concentration is too low, though can obtain higher selectivity, raw material conversion rate is relatively low; When concentration is too high, conversion rate increases, selectivity decreases.

[0045] Note: In the present invention, if there is no special instruction, the selectivity is calculated by gas chromatography peak area, and the calculation formula is: product peak area ÷ sum of product and disubstituted by-product area × 100%, and the yield is based on the converted 2-nitro Toluene meter.

Embodiment 3

[0047] Adopt the method of embodiment 1, adjust the flow velocity of two metering pumps, to change the molar ratio of A, B two stock materials, other parameters are constant, investigate the influence of different molar ratios on reaction result, the results are shown in Table 2:

[0048] Table 2: Effects of different molar ratios (2-nitrotoluene: formaldehyde) on the reaction results

[0049] The molar ratio of 2-nitrotoluene conversion rate selectivity yield 1:1 79.1％ 86.2％ 82.4％ 1:0.9 82.3％ 90.9％ 84.3％ 1:0.8 73.2％ 98.1％ 94.2％ 1:0.7 65.8％ 98.8％ 94.9％ 1:0.6 56.4％ 99.1％ 95.4％ 1:0.5 47.5％ 99.5％ 96.1％

[0050] The results in Table 2 show that the reaction is unfavorable if the molar ratio between the two materials is too low or too high, and it is optimal when the molar ratio of the two materials is 1: (0.8-0.9).

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Abstract

The invention discloses a method for continuously preparing 2-(2-nitrophenyl) ethanol. The method comprises the following steps: carrying out nucleophilic addition reaction on 2-nitrotoluene and formaldehyde in a solvent under the catalytic action of quaternary ammonium base in a tubular reactor by adopting a tubular continuous method to generate the 2-(2-nitrophenyl) ethanol. According to the method, the reaction time is shortened, the alkali consumption is reduced, the reaction selectivity and yield are improved, the energy consumption and the three-waste output are reduced, and the method has good economic benefits and conforms to the era theme of energy conservation and emission reduction.

Description

technical field [0001] The invention relates to a method for continuously preparing 2-(2-nitrophenyl)ethanol. Background technique [0002] At present, indole is an extremely important chemical fuel, which is widely used in medicine, pesticide, fuel and other fields. Many raw materials contain indole structure. The synthesis method of indole mainly contains two kinds at present: the one, traditional Fischer synthetic method, promptly make with the salt of phenylhydrazine and acetaldehyde reaction; Formaldehyde reacts to generate 2-(2-nitrophenyl)ethanol, and then undergoes reduction and cyclization to generate indole. Since the raw material 2-nitrotoluene used in the second method is a by-product of toluene nitration, the cost is lower, so the second method is mainly used in industry at present. [0003] Bibliographical reports prepare the method for 2-(2-nitrophenyl) ethanol a lot, basically take o-nitrotoluene and formaldehyde or paraformaldehyde as raw material, under a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C201/12C07C205/19
CPCC07C201/12C07C205/19
Inventor 叶新沈文光王保军严生虎
Owner CHANGZHOU FEIYU CHEM
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